Mangrove forest study has takeaways for coastal communities

Professor David Lagomasino, an East Carolina University assistant, studied the causes of mangrove forest death in Florida following Hurricane Irma 2017. These findings could have important implications for other states like North Carolina in how they manage their coasts to prepare for extreme weather. Credit: David Lagomasino/ECUA new paper by East Carolina University's Department of Coastal Studies sheds light on the effects of human-made infrastructure on coastal wetlands following major storm events.The study was done in partnership with NASA and Florida International University. It was led by assistant professor David Lagomasino.The research focused on Hurricane Irma's 2017 impact on Florida and the destruction it did to its mangrove forests. The researchers found that forests experienced unprecedented dieback following the hurricane.Although mangrove forests are frequently damaged by hurricanes, Lagomasino stated that Florida forests have demonstrated remarkable resilience in the past because of their structure, location, and species composition. The forests didn't recover at the same pace after Hurricane Irma. Evidence of total dieback after the storm was seen on nearly 11,000 hectares. This is an area the size of 24,000 football fields.Lagomasino stated that this is a serious concern because it prevents the state from flooding and property damage worth more than $11 trillion annually.Lagomasino stated that although there have been storms that caused significant damage in the past, Irma appears to have caused the most severe areas of dieback.The research team identified potential causes of the dieback by studying aerial and satellite footage from the area.Lagomasino stated that "Human-made and natural obstacles can affect the flow of water through an region." Roads and levees, for example, can limit or stop water flow between previously connected areas. A lack of water connection can cause extreme dry conditions or extreme wet conditions. This can have a negative impact on wetland vegetation, which thrives in more stable environments.Lagomasino estimates that 11,000 hectares (or 27,000 acres) of mangrove forests, which were resiliently grown back in the past, have failed to recover at their former levels following Hurricane Irma. Credit: David Lagomasino/ECUHuman-made barriers can increase the time water remains on the surface. This can lead to rapid degradation of fine root material. Saltwater ponding can occur when water flow is blocked by barriers or storm surge.These results will be crucial for future storm planning in Florida and other coastal states such as North Carolina, Lagomasino stated.Lagomasino stated that "what we learned in Florida can help North Carolina and other coast regions." Our results show that areas with high storm surges can be identified by their elevation, connectivity and water level. Low elevation areas are more vulnerable to long-term flooding if they are not connected or have no ability to drain after flooding."This information is important for understanding the resilience and vulnerability of North Carolina's coastal forests and wetlands. It may also help to predict urban areas that might be less resilient to extreme weather events."The study identified several changes that could be made in the future to increase coastal resilience when faced with severe weather events.New metrics to account for storm surge, geology and hurricane rating systemTo identify vulnerable areas, establish field research stations in low-lying regions to assist in establishing underrepresented biological and physical processes.Regular coastal remote sensing surveys are performed to monitor drainage basins, and improve water connectivity.To improve freshwater flow and create new tidal channelsLagomasino stated that he hopes the results of his research will improve the recovery from storms. These areas can be identified in advance so that disaster response can take place faster and minimize the impact.The main takeaway is that hurricanes can cause a lot of destruction due to intense winds. The system's ability to recover over time is not always affected by the severity of the damage. Other factors such as changes in elevation and storm surge play an important role in how the ecosystem recovers from initial damage. These factors can be helpful in reducing long-term effects in vulnerable communities if you keep them in mind before hurricane season.Learn more about NASA's mapping of hurricane damage to Everglades and Puerto Rico forestsAdditional information: David Lagomasino and colleagues, Storm surge, ponding, and mangrove dieback following Hurricane Irma in Southwest Florida, Nature Communications (2021). Information from Nature Communications David Lagomasino and colleagues, Storm surges and ponding explain mangrove decline in southwest Florida after Hurricane Irma (2021). DOI: 10.1038/s41467-22-24253-yEast Carolina University